1. Field of the Invention
The present invention relates to a thermal activation device for thermally activating a heat-sensitive adhesive layer of a sheet material having a printing layer formed on one surface of a sheet-like base material and having the heat-sensitive adhesive layer formed on the other surface, and relates to a printer for performing printing on the sheet material in which the printing layer is provided on the one surface of the sheet-like base material.
2. Description of the Related Art
For example, in a distribution center and shops, labels for displaying various types of information such as prices and for displaying barcodes for management by means of POS (point of sales) terminals have been used by being attached to articles. As this type of label, a proposal has been made of a label, which is issued using a sheet material having a printing layer formed on one surface of a sheet-like base material and a heat-sensitive adhesive layer formed on the other surface thereof.
In general, a label issuing instrument which issues the label having the heat-sensitive adhesive layer as described above includes a sheet supply apparatus that supplies the sheet material, a printing apparatus that prints various types of information on a thermal printing layer of the sheet material supplied from the sheet supply apparatus, a cutting apparatus that cuts the sheet material for which the printing has been performed by the printing apparatus, and a thermal activation device that thermally activates the heat-sensitive adhesive layer of the sheet material.
Basic constructions of the conventional printing apparatus and thermal activation device are similar to each other, and each of the apparatuses has a platen roller for conveying the sheet material, with the thermal head and the thermal activation head being brought into press contact with the platen roller. In each of such conventional printing apparatus and thermal activation device, a so-called clamshell-type construction has been adopted, which includes a platen unit that is movable so as to bring the platen roller into and out of contact with the thermal head or the thermal activation head, and exposes the thermal head and the thermal activation head to the outside of the apparatus, thus facilitating exchange, maintenance, etc. of the heads. Moreover, in each of other conventional clamshell-type printing apparatuses and thermal activation devices, a construction has also been adopted, in which the thermal head and the thermal activation head are movable so as to come into and out of contact with the platen roller.
Moreover, each of the conventional clamshell-type printing apparatus and thermal activation device includes a platen lock mechanism for locking the platen unit so as to fix movement thereof in a state where the thermal head or the thermal activation head is brought into press contact with the platen roller.
With regard to the conventional clamshell-type printing apparatus, a construction including a platen lock mechanism having a lock arm engaged with a shaft portion of the platen roller has been disclosed (for example, refer to JP 2003-200624 A).
Likewise, as shown in FIG. 11, a conventional thermal activation device 110 includes a platen lock mechanism 119 for locking a thermal activation head 111 into press contact with a platen roller 112. The platen lock mechanism 119 has a lock arm 132 provided so as to be rotatable. In the lock arm 132, an engagement groove 137, which is engaged with an outer peripheral portion of a bearing 126 that holds a rotary shaft 125 of the platen roller 112 so as to be freely rotatable, is formed by being notched.
The platen lock mechanism 119 operates to rotate the lock arm 132. Thus, an engaged state of the bearing 126 of the platen roller 112 and the lock arm 132 is released, and a platen unit (not shown) which supports the platen roller 112 is rotationally driven in a direction of an arrow c2, and the platen roller 112 is moved to a position spaced apart from the thermal activation head 111. Meanwhile, in the platen lock mechanism 119, the platen unit (not shown) which supports the platen roller 112 is rotationally driven in a direction of an arrow c1, the platen roller 112 is moved into press contact with the thermal activation head 111, and the bearing 126 of the platen roller 112 and the engagement groove 137 of the lock arm 132 are engaged with each other.
As described above, the platen lock mechanism provided in the conventional clamshell-type printing apparatus or thermal activation device has the lock arm engaged with the rotary shaft of the platen roller or the outer peripheral portion of the bearing thereof.
Hence, in the conventional printing apparatus or thermal activation device, an operation range of the rotating lock arm is relatively large, and a conveyor roller is placed at a position not inhibiting the movement of the lock arm. When the operation range of the rotating lock arm is to be secured, a distance between the conveyor roller and the platen roller cannot be shortened. Accordingly, it has been difficult to achieve miniaturization of the entire apparatus.
Moreover, because the distance between the conveyor roller and the platen roller cannot be shortened, a sheet material that is a cut sheet shorter than the distance between the conveyor roller and the platen roller cannot be conveyed, and it has been impossible to handle such a relatively short sheet material.
Furthermore, in the conventional thermal printer, the operation range of the lock arm is relatively large, and accordingly, in the case of using a compression coil spring which urges the lock arm, it is necessary to ensure relatively large compression for the compression coil spring. This leads to enlargement of the compression coil spring, and thus it has been difficult to miniaturize the entire apparatus.